T-cell receptor γ gene rearrangement in cutaneous T-cell lymphoma: comparative study of polymerase chain reaction with denaturing gradient gel electrophoresis and GeneScan analysis

Summary Background  The usefulness of T-cell receptor gene rearrangement (TCR-GR) analyses for differentiating cutaneous T-cell lymphoma (CTCL) from benign inflammatory disorders (BID) has been insufficiently studied to date. Objectives  To evaluate the diagnostic value of TCR-GR analyses, comparing polymerase chain reaction (PCR) with denaturing gradient gel electrophoresis (DGGE) analysis and BIOMED-2 standardized protocol PCR with GeneScan analysis (BIOMED-2-GS). Methods  Both types of PCR were performed in 157 patients evaluated for initial features suggestive of CTCL between 1996 and 2007. After clinical and histological review, the final diagnosis was CTCL in 77 cases and BID in 80 cases. Results  DGGE and BIOMED-2-GS had a similar diagnostic value for distinguishing CTCL from BID, with a sensitivity of 74% and 77%, respectively, and a specificity of 86%. The observed concordance between both methods was 90% and the kappa coefficient was 0·79. Positivity rates did not depend on the PCR method but varied according to the type of CTCL (73–75% in mycosis fungoides, 90–100% in Sezary syndrome, 40–60% in lymphomatoid papulosis and 100% in other types). The positivity rate in BID was 14% with both methods. The most frequent BID with a monoclonal pattern were drug-induced cutaneous lymphoid hyperplasia, erythrodermic psoriasis and pityriasis lichenoides chronica. Conclusions  BIOMED-2-GS analysis of the TCRγ gene is as sensitive and specific as DGGE for CTCL diagnosis. In addition, BIOMED-2-GS is less time-consuming and gives more information concerning the size and nature of TCR-GR.